Iodine purifies water by oxidizing the membranes and organelles of water-born pathogens, upsetting their biological functions and causing them to die. Iodine treatment is a fast and cost-effective way to neutralize pathogens in freshwater for drinking.
Iodine is highly electronegative, making it an exceptional oxidizing agent. The membranes and organelles of bacteria are suspect to oxidation. When iodine reacts with these living structures, the compounds composing these structures are oxidized, while the iodine atoms are reduced to negative iodide ions, upsetting the ion balance of the pathogens, leading to their death.
Iodine kills off many pathogens in natural freshwater sources. It is an imperfect but lightweight and effective way to purify drinking water in the field. Camping stores stock iodine purification kits consisting of an iodine pill and taste neutralizer to remove the unpleasant taste that iodine purification yields. Taste neutralizers precipitate the iodine and should be added after giving the iodine sufficient time to neutralize water-born pathogens. These neutralizers include ascorbic acid and active carbon.
Iodine is light sensitive and must always be stored in a dark bottle to prevent spoilage. The maximum recommended dietary dose of iodine is 2 milligrams per day, while the maximum recommended duration of use is three weeks, according to the U.S. National Library of Medicine. People who have thyroid problems, are on lithium or are pregnant should consult a physician before using iodine-based water purification.